Control of Tongue Position in Patients with Obstructive Sleep Apnea: Concept and Protocol for a Randomized Controlled Crossover Trial.

We hypothesize that the control of tongue position using a newly developed tongue position retainer, where the tongue is held in a protruded position (i.e., intervention A) or in its resting position (i.e., intervention B), is effective for maintaining upper airway patency in obstructive sleep apnea (OSA) compared with no control of tongue position. This is a randomized, controlled, non-blinded, crossover, and two-armed trial (i.e., sequence AB/BA) in 26 male participants (i.e., sample size) who are scheduled to undergo a dental operation under intravenous sedation with OSA (10 ≤ respiratory event index < 30/h). Participants will be randomly allocated into either sequence by a permuted block method, stratified by body mass index. Under intravenous sedation, participants will undergo two interventions, separated by a washout period after receiving intervention A or intervention B using a tongue position retainer after baseline evaluation, before each intervention is provided. The primary outcome is the abnormal breathing index of apnea as determined by the frequency of apnea per hour. We expect that, compared with no control of tongue position, both intervention A and intervention B will improve the abnormal breathing events with superior effects achieved by the former, offering a therapeutic option for OSA.

Whole Blood Platelet Aggregation Test and Prediction of Hemostatic Difficulty After Tooth Extraction in Patients Receiving Antiplatelet Therapy.

When patients on antiplatelet therapy (APT) require minor invasive surgery, APT is usually continued to limit the risk of thrombosis. However, the possibility of hemostatic difficulties necessitates the monitoring of platelet aggregation to prevent unexpected bleeding. We examined whether whole blood aggregometry as a point-of-care testing (POCT) could be useful as a tool for predicting hemostatic difficulties. Sixty-five patients receiving APT and 15 patients who were not receiving APT were enrolled in the present study; all patients were scheduled to undergo a tooth extraction. Whole blood samples were obtained and were examined using multiple electrode aggregometry. The aggregometry was performed using arachidonic acid (AA), adenosine diphosphate (ADP), and thrombin receptor activating peptide. Hemostatic difficulty was defined as a need for more than 10 minutes of compression to achieve hemostasis. The AA test results were significantly lower in patients treated with aspirin (control: 97.7 [29.0] U, aspirin: 14.5 [7.2] U, P < .001). The ADP test results were also significantly lower in patients treated with a P2Y12 inhibitor (control: 77.7 [21.7] U, P2Y12 inhibitor: 37.3 [20.4] U, P < .01). Six of the examined cases exhibited hemostatic difficulties. The cutoff values for the prediction of hemostatic difficulty were 16.5 U for the AA test (sensitivity, 0.833; specificity, 0.508) and 21 U for the ADP test (sensitivity, 0.847; specificity, 0.500). Our study showed that whole blood aggregometry was useful as a POCT for the prediction of hemostatic difficulties after tooth extraction in patients receiving APT.

Anesthetic Management Using a Laryngeal Mask Airway in a Child With Congenital Bronchial Atresia.

Congenital bronchial atresia is a relatively rare malformation that causes a segmental obstruction of the bronchus during the fetal period. The peripheral lung distal from the obstructed bronchus becomes hyperinflated because of the unidirectional flow through collateral check-valve entry. Positive pressure ventilation during general anesthesia may cause a rupture of the bulla, resulting in pneumothorax. An 8-year-old girl, who had to undergo oral surgery, was diagnosed as having congenital bronchial atresia and one-fifth of her lung was poorly ventilated. We planned to perform general anesthesia under spontaneous respiration using a laryngeal mask, which was well tolerated.

Optimal and safe standard doses of midazolam and propofol to achieve patient and doctor satisfaction with dental treatment: A prospective cohort study.

BACKGROUND: The incidences of morbidity and mortality caused by pharmacosedation for dental treatment have not yet reached zero. Adverse events are related to inappropriate respiratory management, mostly originating from an overdose of sedatives. Since sedation is utilized for the satisfaction of both the dentist and the patient, the optimal dose should be minimized to prevent adverse events. We attempted to define the optimal doses of midazolam and propofol required to achieve high levels of patient and dentist satisfaction. METHODS: One thousand dental patients, including those undergoing third molar extractions, were enrolled in this study. A dose of 1 mg of midazolam was administered at 1-minute intervals until adequate sedation was achieved. Propofol was then infused continuously to maintain the sedation level. Both the patients and the dentists were subsequently interviewed and asked to complete a questionnaire. A multivariate logistic regression analysis was used to examine the factors that contributed to patient and dentist satisfaction. RESULTS: The peak midazolam dose resulting in the highest percentage of patient satisfaction was 3 mg. Both a lower dose and a higher dose reduced patient satisfaction. Patient satisfaction increased with an increasing dosage of propofol up until 4 mg/kg/hr, reaching a peak of 78.6%. The peak midazolam dose resulting in the highest percentage of dentist satisfaction (78.8%) was 2 mg. Incremental propofol doses reduced dentist satisfaction, in contrast to their effect on patient satisfaction. The strongest independent predictors of patient satisfaction and dentist satisfaction were no intraoperative memory (OR, 5.073; 95% CI, 3.532-7.287; P<0.001) and unintentional movements by the patient (OR, 0.035; 95% CI, 0.012-0.104; P<0.001), respectively. No serious adverse events were reported. CONCLUSION: We found that 3 mg of midazolam and 3 mg/kg/hr of propofol may be the optimal doses for maximizing both patient and dentist satisfaction. Although this level of sedation is relatively light, memory loss and an absence of unintentional patient movements can be expected without adverse events.

The Amount of Fluid Given During Surgery That Leaks Into the Interstitium Correlates With Infused Fluid Volume and Varies Widely Between Patients.

BACKGROUND: The revised Starling law suggests that intravenously infused fluid may leak into the interstitium and not remain in the intravascular space. This hypothesis is supported by clinical findings that postoperative weight gain is proportional to the amount of infused fluid. The distribution of intravenously administered fluid between the interstitium and intravascular space deserves evaluation, as postoperative weight gain because of intraoperative infusion is an important risk factor for postoperative adverse events. We quantitatively estimated fluid movement in patients undergoing orthognathic surgery by performing a volume kinetic study using hemoglobin concentration as a marker of dilution. METHODS: Forty-one patients scheduled to undergo orthognathic surgery were enrolled in this study. The arterial hemoglobin concentration was measured at each procedural step. Acute normovolemic hemodilution was induced by withdrawing 400 mL of blood followed by the infusion of a known amount of hydroxyethyl starch, enabling the initial blood volume to be estimated. The dilution rate of the arterial hemoglobin concentration enabled the volume of fluid in the intravascular space to be quantified. The fluid volume that leaked into the interstitium was then calculated based on the change in the estimated intravascular plasma volume. RESULTS: The blood volume estimated via this method was close to the value derived from a previously published formula. The mean volume of crystalloid infused as a maintenance fluid was 2062 ± 408 mL, ranging from 1220 to 3050 mL. None of the cases required blood product transfusion. The amount of infused fluid that remained intravascular varied widely from 2.0 to 35.7 mL/kg (mean, 12.0 ± 8.2 mL) after surgery, corresponding to 5.3% to 95.7% of the infused volume. The change in intravascular fluid volume during surgery was not strongly correlated with the infusion amount (Pearson correlation analysis: r = -0.05, P = .75, -0.44 < ρ ≤ 0.35, confidence intervals; Spearman correlation analysis: r = -0.14, P = .38, -0.51 < ρ ≤ 0.27). However, the amount of fluid that leaked into the interstitium during surgery did correlate with the infusion amount (Pearson correlation analysis: r = 0.42, P = .01, 0.03 < ρ ≤ 0.70; Spearman correlation analysis: r =0.45, P = .003, 0.07 < ρ ≤ 0.72). CONCLUSIONS: We found that the increase in intravascular fluid volume caused by intravenous fluid administration was not correlated strongly with the volume of infused fluid. Instead, the amount of fluid leakage into the interstitial space depended on the infused fluid volume. This clinical result supports the revised Starling law, which suggests that intravascular fluid may often leak into the interstitium. More work is needed to better understand the factors governing leakage of infused fluid into the interstitial space.

[Successful anesthetic management of three patients receiving pheochromocytoma resection using extremely high-dose remifentanil infusion].

We describe three consecutive cases of successful anesthetic management for pheochromocytoma resection under balanced anesthesia with sevoflurane inhalation and extremely high-dose remifentanil infusion. This case series aimed to examine whether the aggressive dosing of remifentanil, exerting both depressor and bradycardic actions with short durations, is applicable for hemodynamic control during pheochromocytoma resection. The remifentanil infusion rate was set to maintain the systolic arterial pressure below 150 mmHg and heart rate below 100 beats x min(-1). In 2 of 3 cases, intraoperative hemodynamics were controlled by titrated remifentanil infusion with up to 2 and 3 microg x kg(-1) min(-1) in each case, without additional vasoactive agents. In another case, since adequate antihypertensive control was ineffective despite incremental remifentanil infusion to a maximum of 5 microg x kg(-1) x min(-1) supplemented with repeated boluses of 200 microg remifentanil, a total of 2.4 mg of nicardipine as a depressor was needed. Ephedrine 12 mg was employed following tumor removal. This anesthetic regimen thus allowed minimal or no concomitant use of depressors during tumor manipulation and vasopressors following tumor removal. In conclusion, the liberal use of remifentanil for the anesthetic management of pheochromocytoma resection appears to be simple, safe and effective.

[Responses of hemodynamics and splanchnic organ blood flow to esmolol during inhalation of volatile anesthetics in dogs].

BACKGROUND: Because the hemodynamic alterations due to sympathetic suppression by the interaction of esmolol with volatile anesthetics may alter the blood flow to the splanchnic organs, this study was designed to investigate whether esmolol might modify the hemodynamics and splanchnic organ blood flow in anesthetized dogs. METHODS: Anesthesia was maintained with 0.9% halothane, 1.3% isoflurane or 2.4% sevoflurane (1MAC, n=8, each) in oxygen. Esmolol was infused at a constant rate of 400 microg * kg(-1) x min(-1) during a 60 min-infusion period. The renal, hepatic, and pancreatic blood flows (RBF, HBF, and PBF) were measured by using the hydrogen clearance method. RESULTS: Mean arterial pressure in all three groups decreased without any changes in heart rate or systemic vascular resistance. Cardiac index in all three groups decreased with reductions in cardiac contractility. The RBF, HBF, and PBF in all three groups were reduced during the esmolol infusion. CONCLUSIONS: The splanchnic organ blood flow reductions caused by esmolol may be due to cardiac depression, whereas there appears to be no differences in there change regarding the kind of the volatile anesthetics. These findings suggest that hypotension induced by esmolol may impair the maintenance of splanchnic organ blood flow during anesthesia by volatile agents.

Esmolol attenuates hepatic blood flow responses during sodium nitroprusside-induced hypotension in dogs.

PURPOSE: The hemodynamic responses secondary to sympathetic suppression by esmolol may alter blood flow to splanchnic organs. We investigated whether esmolol might modify splanchnic organ blood flow responses during sodium nitroprusside (SNP)-induced hypotension in dogs anesthetized with sevoflurane. METHODS: The control group (n = 10) received SNP (SNP group). The ES25 and ES100 groups (n = 10, each) received SNP combined with esmolol infused at a constant rate of 25 and 100 micro g*kg(-1)*min(-1) during the hypotensive period after a mean arterial pressure (MAP) of 60 mmHg was attained by the infusion of a 0.03% SNP solution, respectively. The renal, hepatic, and pancreatic blood flows (RBF, HBF, and PBF) were measured by using the hydrogen clearance method. RESULTS: Cardiac index in the SNP group increased (P < 0.01), but in the ES groups it decreased (P < 0.01). Left ventricular dP/dtmax in the SNP group remained unchanged, but in the ES groups it decreased (P < 0.01, each) during the hypotensive period. Except for HBF in the SNP group, the splanchnic blood flow in all groups decreased (P < 0.01, each). The HBF in the ES groups was lower than that in the SNP group (SNP vs ES25, ES100; 70 +/- 1 vs 64 +/- 5, 6 3 +/- 3 mL*min(-1)*100 g(-1)). CONCLUSIONS: This study shows that the differences in HBF between SNP-induced hypotension with or without esmolol may be due to the changes in cardiac output caused by alterations of cardiac contractility. These findings suggest that a small dose of esmolol may impair the maintenance of HBF during SNP-induced hypotension.